Power supply system



y 1932- H. MJSTOLLER 1,856,665

POWER SUPPLY SYSTEM F iled Dec. 12, 1923 ut'n'nnnnnu v fizz/7 M. .ffa/kr6 a i )5;

Patented May 3, 1932 V UNETED STATES PATENT OFFICE HUGH M. srOLLER, orMOUNTAIN LAKES, NEW JERSEY, ASSIGNOR'TO WESTERN unno- TRIC COMPANY,INCORPORATED, 013 NEW YORK, N. Y., A CORPORATION OF NEW YORK POWERSUPPLY SYSTEM Application filed. December 12, 1923. Serial No. 680,172.

This invention relates to transmission system and more particularly topower systems for radio and amplifying systems, includ-, ing electrondischarge devices of the threeelement type.

An object of the invention is to supply the necessary electrical energyfor electron discharge devices from standard commercial lightingsystems.

Various arrangements have been suggested heretofore for heating thefilaments of vacuum tubes by alternating current of the frequenciesusually obtainable from commercial power lines. With these arrangementsit has been practicable to reduce the audible frequency. disturbance toa negligible amount onlyin amplifiers having one or two stages or .whereonly the last one or two stages of a multi-stage system are providedwith alternating current heating. It has also been found impracticableto use low frequency currents to heat the cathodes of vacuum tubes usedas detectors of high frequency currents.

In accordance with this invention it is possible to heat the cathodes ofelectron discharge devices used both for detecting and amplifyingpurposes by alternating current without introducing objectionabledisturbances. They may also be so heated when more than two dischargedevices are conn-ected in tandem.

In carrying out the invention an alternating current of a super audiblefrequency is supplied to the electron discharge devices, which may beused both for radio receiving and amplifying purposes, to heat theoathodes of such devices.

More specifically, the invention contemplates the provision of a vacuumtube oscillation generator which is operated by a current derived from avacuum tube rectifier set, and which supplies to the respective circuitscurrents of a super audible frequency for lighting the filaments of thedischarge devices of both the reoeivingand amplifying systems. As shownherein the invention is applied to a radio receiving system, and thefilament heating current supplied to the radio frepjuency portion of thecircuit is of a super audible frequency, which is also low enough thatit does not combine with the radio frequencies to form audible frequencycomponents.

The potentials for theplate electrodes of the respective electrondischarge devices are supplied from the vacuum tube rectifier setthrough a potentiometer which gives the requlred potentials to therespective plate electrodes. In order to enable the use of the powersystem or current supply set by amateurs, suitable means is provided topermit the operation of the vacuum tube rectifier set by currentsderived from commercial or residence lighting systems.

Other objects of the invention will be apparent from the followingdetailed description and claims.

In the single figure of the drawing, one embodiment of the invention isillustrated.

Referring now to the drawing, there is shown a radio receiving system, Aan am plifying set B, a loud speaking receiver C and a power system orcurrent supply set D.

The radio receiving system A comprises an antenna 7 which is connected,to ground through an adjustable condenser 8, an inductance 9, and theprimary winding of an adjustable coupling 10. The secondary winding ofthe adjustable coupling 10 is connected to the input circuit of a vacuumtube 13 which serves as the first stage of radio frequencyamplification. Connected in bridge of the input circuit of the vacuumtube 13 is an adjustable condenser 14 for increasing the selectivity ofthe circuit. Following the vacuum tube 13 is a vacuum tube 16, which isconnected to the vacuum tube 13 by means of a radio frequencytransformer 17. The vacuum tube 16, likevacuum tube 13, functions as anamplifier of waves of the radio frequency, it being now well-known thatbetter results are obtained through the amplification of the waves priorto their detection. It is, of course, understood that although twostages of radio frequency have been shown, obviously other stages may beadded if desired.

Inductively coupled by vacuum tube 16, through transformer 19 is avacuum tube 20 serving as a detector of the radio signal waves.- Asshown the detection is of the type in which there is provided in thegrid circuit of the vacuum tube a grid leak 21 consisting of aresistance and a condenser. Following the vacuum-tube 2 0 or thedetector is avacuum tube 25 which'is connected to the output circuit ofthe detector20 by means of a transformer 26, and which serves as anamplifier of the audible frequency waves. I

The amplifier set E is connected to the.

I ed to the output circuits of the vacuum tubes 31and 82 through atransformer 33.

The current for heating the filaments of the electrondischargedevicesmaking up the receiving systemA and those in theamplifier set B, and the potentials for the plate electrodes "thereof,are supplied from a power system or current supply set D. In the systemillustrated the alternating current generator 36 which is showndiagrammatically to illustrate a standard commercial or residencelighting system of 110 volts at a frequency of 60 cycles is connected tothe primary winding'of a transformer 37 for stepping up the voltage toapproximately 1,000 volts. The turns of the secondary winding of thetransformer 37.is divided into a number of different sets 38, 39 and 40.The set 38 is connected to the cathodes of a pair of'vacuum tuberectifiers41 and 42through which the cathodes receive current forheating them to incandescence. The secondary 39 is con nected tothe-plate electrodes of the vacuum tube rectifiers 41 and 42, whichserve to rectify the alternating current. The resulting direct currentserves to supply the plate circuits of the electron discharge devices ofthe radio receiving system A, the amplifier set B and the oscillationgenerator D. I I

As illustrated the oscillation generator comprises a vacuum tube 45which has its filament connected to the secondary 40 of the transformer37 whereby alternating current is supplied to its filament forheating-it to incandescence, and which has its grid and plate electrodesconnected to inductance coils '47 and 48. The inductance coils 47 and 48are winding 39 and the filaments of the rectifier tubes. A condenser 49is connected between the coils 47 and 48 which are bridged by 21condenser 50. These elements taken together, constitute the oscillationcircuit. The impedance of condenser 49, however, is low as compared withthat of condenser 50, and the latter provides most of the condensivereactance for determining this frequency. 7 By selecting the values ofthese elements the frequency generated by the oscillation generator maybe made almost any desired value. In the present case it is desired thatthe frequency be high, say in the super-audible range. Therefore, thesize of the inductances 47 and 48'and the condenser 50 must be small. Inorder to prevent the-flow of direct current to the coil 48 a blockingcondenser 51 is connected between the plate electrodes'and this'coiLfAlso to prevent the introduction of objectionable disturbancescaused by the harmonics of the alternating current generator36 and therectifier tubes 41 and42, a filter consistingof inductance 56andcondenser 57 is connected in the direct current supply circuit.Connected between the coil 47 and the grid elec trode of tube 45 is agrid leak 52 comprising a resistance which in combination with acondenser maintains the average grid potential of the oscillatingtube 45at a suitable negative value. v

lVith the arrangement described, when current starts to flow in theplate circuit of tube 45, current is induced from coil-48 to coil'47thereby changing the charge on the grid electrode. The resultant changeproduces a change in the current in the plate circuit. When the gridbecomes more negative by the current thus produced, the current in theplate circuit decreases, while'if the grid is made more positive, theplate current increases. These variations cause an'a'lternating currentto flow, the frequency of which is dependent upon the applied potentialand the values of the inductances 47 and 48 and condenser 50.

The type of oscillation generator shown in the present case is similarto that of Patent No. 1,47 2,470 to R. V. L. Hartley, and sincethe'generator itself is not being claimed, a more detailed descriptionthereof is believed unnecessary.

The current for heating the filaments of the electron discharge devicesof the receiving system which is made up of devices 13, 16, 20 and 25,is derived from the oscillation generator by taking the potential dropacross the condenser 49. .It should be noted that one terminal of thecondenser 49 is grounded, therefore'the filaments of the devices 13, 16,20 and 2 5 are at substantially ground potential. Due to the highharmonics of the current generated certain frequencies are pro ducedwhich approach the frequency of the radio wavesand which might introduceobjectionable disturbances in the operation ,bf the electrondischargedevices as,'for example, by beatlng with the radio. frequencies.

Therefore, toprevent the impression of the higher harmonics on thefilaments a filter consisting of an air core inductance 59 and acondenser 60 is connected in the circuit extending between the condenser49 and the filaments of devices 13, 16, 20 and 25. The condenser 49,being of low impedance to the harmonics, serves also to aid in theirsuppression. There is also connected in this circuit .an adjustableresistance 61 to permit of variation in the filament current.

. It should be noted that a vacuum tube is employed for detectingpurposes and that'radio amplification occurs in more than one stage andin spite of the fact that the filaments are lighted by. alternatingcurrent no appreciable hum or disturbance is produced in the loudspeaking receiver C. Such result is due primarily to the fact that highvoltages and small current .are employed in the primary circuit of theoscillator.

The filter consisting of inductance 56 and condenser 57 as is wellknown, tends to store or delay the action of the current delivered bythe vacuum tube rectifiers ll and 42 to the oscillation generator. Inorder that the current delivered by the oscillation generator will befree from modulation, the filter consisting of the condenser 57 and theinductance 56-should be operated at a high flux density of courseallowing a reasonable factor of safety. is dependent only on the numberof ampere turns, while with regard to the condenser 57, the energystored is dependent primarily on the voltage. The energy of thecondenser may be comp'uted by the use of the following formula: V

Energy= C E where C is the capacity of the condenser and E the voltageapplied to the condenser. It is seen from the above formula that byusing a high voltage and small current the condenser may function atsubstantially its maximum flux density, thereby providing a moreefiicient filter without increasing the capacity. With such anarrangement a current is delivered to the oscillation generator freefrom ripples and harmonics, therefore it is possible for the oscillationgenerator to generate an alternating current of a high frequencysubstantially free from modulation. Since there is no appreciablemodulation in the current generated by the oscillation generator, theelectron discharge devices may be satisfactorily operated on alternatingcurrent without the objectionable hum and disturbances which have beenheretofore present in such systems, especially in ",cases where anattempt has been made to pperate the dectector tube on alternatingcurnent.

In one example of the arrangement above d scribed, where the outputenergy required In the case of the inductance 56, it

of the oscillator was 20 watts, the oscillator tube was designed to workwith a plate voltageof 750 volts, thus giving the high voltage and lowcurrent desired for eflicient operation of the direct current filter.The filaments of the devices 29, 31 and 32 which make up the amplifierset E are lighted by the current induced in coil 62. The harmonics ofthe oscillator which, as above stated, are excluded from the circuit A,are included in the heating current for the audio-frequency amplifier.The output efficiency of the oscillator is thus considerably greaterthan that of the usual type of oscillator which is required to produce apure sine wave of one frequency.

The potentials of the plate electrode of the respective electrondischarge devices are derived from the vacuum tube rectifiers 4:1 and42, the gradation of the potentials being obtained by the use of apotentiometer consisting of resistances 65, 66 and 67. In accordancewith the established practice the plate electrode of the detector device20 is supplied with 22 volts, taken at a point between resistances 65and 66, and the potential of 45 volts for electrodes of tubes 13, 16 and25, taken from the point between resistances 66 and 67. Now in the caseof the plate electrodes of the electron discharge devices 29, 31 and 32,which require a higher potential, approximately 120 volts the supply istaken from the resistance 67 through another resistance 68. Couplingbetween various stages of the receiver and amplifier is prevented by theuse of condensers 69, 70 and 71.

In order that the rectified current impressed on the plate circuits willbe free of disturbances a choke coil 72 is connected in the connectionleading from the rectifier tubes 41 and 42 to the potentiometer. Such achoke coil serves to further smooth out the current rectified by therectifiers. The choke coil 72 also serves to prevent the oscillations ofthe oscillation generator from being impressed on the plate electrode.The value of the inductance of the choke coil 72 should be such that thecondensers 69, 70 and 71 and the inductance will not resonate at theripple frequency of the rectifier, this frequency being twice thefundamental impressed.

Although the invention has been disclosed and described with referenceto a particular circuit arrangement, it is of course obvious thatvarious alterations and modifications may be made without departing fromthe spirit'and scope of the present invention.

The invention claimed is:

1. In combination, a plurality of thermionic discharge devices certainof which operate'at low anode potentials, a source of alternatingcurrent energy, a thermionic discharge tube oscillation generator forproducing ultra-audio oscillations, means for heating the cathode ofsaid oscillator tube from said source of alternating current energy,

highanode voltage to said oscillation generator tube. I

8.. The combination defined in claim 1 and in which said plurality ofdischarge oevices operate in tandem in a high-frequency translatingsystem, said oscillation generator having one output circuit forsupplying cathode heating current to the initial devices and anothercircuit for supplying cathode heating current to the final devices ofthe tandem arrangement, said first circuit including a filter forsuppressing harmonics of the generated oscillations.

4."A system for energizing from a single source of alternating currentenergy a plurality of thermionic discharge tubes connected in tandem,one of which'is a detector, comprisinga thermionic discharge tubeoscillat tion generator of ultraaudio frequency oscillations having acathode heated-by current from said source, a rectifier for supplyingrectified anode potential from said source to the anodes of all of saiddischarge tubes including said oscillation generator tube, and

connections for supplying the ultra-audio frequency oscillations fromsaid generator to the cathodes of said plurality of thermionic devices,the anode potential of said 0s cillation generator being many timesgreater than that of said detector.

5. A current supply system for vacuum space discharge devices havingcathodes and anodes comprising a low frequency source of alternatingcurrent, a vacuum tube rectifier for converting said alternating currentto direct current, means for supplying the direct current directly tothe anodes of said discharge devices, a vacuum tube oscillator separatefrom said devices, energized from the output of sald rectifier forgenerating high frequency current, and means to supplysaid highfrequency current to the cathodes of said discharge devices.

I 6. A current supply system for vacuum space discharge devices havingcathodes and anodes, comprising a 10W frequency source of alternatingcurrent, a vacuum tube rectifier for converting said alternating currentto direct current connected to said source, a plurality of circuitbranches for the output circuit of said rectifier, one of said branchesincluding the anodes and cathodes of said ing filament and platecircuits, an oscillation generator for generating currents. of ultraaudio frequency differing from the received signal frequency,connections for supplying power to said plate circuit and to saidgenerator, and connections'for supplying oscillating filamentheating-current from said generator to said filament circuit.

8. in combination, a'radio receiver having plate and filament circuits,anultra audio frequency oscillation generator for generating currents ofultra audio frequency difi'ering'from the received signal frequency,connections for supplying power to said plate circuits and saidgenerator, connections for supplying oscillating filament heatingcurrent froms'aid generator to said filament circuits, and means forpreventing modulation of the ultra audio frequency output of theoscillation generator.

9. The method of operating a thermionic valve having a cathode and acontrol electrode which comprises heating the cathode thereof by ultraaudio frequency oscillating current and maintaining the controlelectrode thereof sufiiciently negative with respect to the cathode toprevent any substantial flow of current through the control electrode.

In witness whereof, I hereunto subscribe my name this 5th day ofDecember, A. D.

